The longtime San Francisco 49ers season ticket holders who were priced out of the Santa Clara era weren’t the only ones missing from last Sunday’s inaugural football game at Levi’s Stadium. For anyone who has been going to sporting events for many years, something else was conspicuously lacking in the crowd at the $1.3 billion palace next to the Great America amusement park.

Children.

Long gone are the days when one of the signature scenes of an American sporting event was a parent taking a child — or two or three — through the turnstiles. Children were few and far between at Levi’s, and for understandable reason: season tickets at even the extremities of the sun-seared top eastern deck require seat licenses starting at $2,000, not counting the $131 cost of a seat for prime games, or parking and concessions.

The cost goes up from there. Way, way up.

I can’t begrudge the 49ers for optimizing revenue in a largely privately financed stadium. They didn’t start this trend, and it’s coming soon to that new Warriors arena in San Francisco. Far better for these teams to cater to the fat cats and to vacuum out the wallets of the fanatics than to put a general burden on taxpayers who may or may not care about a Gore who never served as vice president of the United States.

But about that absence of children:

Does it matter to the professional sports leagues — especially the NFL and NBA, where tickets for premium seats exceed triple digits — that attendance is less and less often a family affair? Will it come back to haunt these sports when today’s youths reach their 20s and 30s and think of sports as something to be experienced in the living room while noodling on the iPad or its future equivalent? Will the games seem quite as compelling if the passion in the stands — now passed from generation to generation — is no longer there?

I put the question to Carmen Policy, former executive from the team’s glory years who later became president and CEO of the Cleveland Browns expansion franchise. He agreed: The dearth of kids at NFL games is a growing problem.

I have a theory that many of the fans who like to see games in person — such as me — were introduced to the grandstands at an early age. Tickets always seemed easily accessible. One of my father’s workmates was a 49ers season ticket holder at Kezar Stadium who enjoyed the company of an appreciative 6-year old who didn’t yet know the definition of a first down or the pronunciation of Packers (”Packlers,” I said until repeatedly corrected). My uncle, who owned an Oakland welding business but had absolutely no interest in football, bought six season tickets to the Raiders games at Frank Youell Field out of a sense of civic obligation, and unloaded them to family and friends. My dad took me to more sporting events than I can count, including San Francisco Warriors games at Civic Auditorium with discount coupons I clipped from Bob Ostrow salami wrappers.

I still have a ticket from the first Raider game at the Oakland-Alameda County Coliseum on Sept. 18, 1966. Price: $5.50. That works out to about $40 in today’s dollars, or enough to get you into one of the outer parking lots at Levi’s.

Good times, generating so many distinct sayings and rituals, which I created anew with my own child.

Policy has heard a thousand similar stories.

“So many of the memories that people talk to me about relative to the 49ers were: 'I went with my dad.’ 'I went with my uncle.’ 'My mom and dad would take me and my brother.’ And a lot of women shared the experience of having that moment with their fathers . . . and their mothers, too, but for some reason it always used to be all the more important ot be their with their fathers, experiencing something that their dads obviously cared a lot about. And the were part of it. The sense was, it brought them closer.

“And now . . . they are 49ers fans,” said Policy.

Roger Noll, a Stanford economist who focuses on the business of sports, noted that young people today “play sports as much as my generation did” but are less likely to attend games or even watch them on television.

“In 25 years, when a majority of the adult population will have grown up on high-speed Internet, will the interest in major league sports be as high?“ Noll asked. “I suspect this is the biggest challenge for sports.“

More Information

Tickets: Licenses for the right to buy season tickets start at $2,000. Single-game tickets for upper-level seats can range from $43 for a preseason game to $131 for one of the marquee regular season games. Premium sideline seats can run up to $569 each (on top of $80,000 seat license) for the most desirable games.

Parking: $40 to $50 for the masses (many times that for the reserved spots up close to the stadium)

Professional sports is facing a quandary: The home viewing experience has been greatly enhanced by high-definition television and the ability to follow multiple games or engage in social media at the same time. Levi’s Stadium offers answers to those who might be tempted to stay home: padded seats in the priciest locations, enormous video screens with remarkable clarity and brightness, wide concourses with myriad upscale food and drink choices. I even spotted a video game kiosk last Sunday that was attracting a gathering crowd as the 49ers-Broncos game devolved into a blowout.

Yet part of what makes the game so appealing is the atmosphere, the emotion and sense of urgency in the crowd: Technology brings you there. But what if there is no there there?

“We’re building our monuments in a way that precludes (families with children) from coming instead of making the door easy to open,” Policy said. “I think it’s something that we’re really, really dropping the ball on.”

John Diaz is The San Francisco Chronicle’s editorial page editor. E-mail: jdiaz@sfchronicle.com On Twitter: @JohnDiazChron